Interconnect scheme for mounting differently configured print heads on the same carriage

Abstract: A printer/plotter having a carriage (50) for removably mounting a plurality of printheads, with one type of printhead (64) such as a wider swath higher resolution black inkjet cartridge having one type of electrical interconnect and another type of printhead (40) such as a narrower swath lower resolution color inkjet cartridge having a different type of electrical interconnect. The carriage includes differently configured flex-circuit conductive assemblies (62; 54,56,58) for each different type of electrical interconnect without having to change the datum configuration of the cartridges mounted in the carriage.

Description: BACKGROUND OF THE INVENTION This invention relates generally to printers/plotters, and more specifically to print carriages having inkjet print cartridges removably mounted thereon. It is common to have several inkjet print cartridges in a single carriage of an inkjet printer. But in some instances these cartridges may have different capabilities and therefore have different electrical interconnect designs connecting the cartridges to the printer. For example, the number and pattern of electrical contacts may differ between the different types of cartridges, such as in cartridges which have different print resolutions, see e.g. EP-A-492 955. Many multi-pen set printers have addressed the issue of improving output quality and the speed of output without increasing the resolution of the entire pen set and thus their cost and complexity. Some have improved output quality through improved addressability and some through improved printing algorithms. In such cases the improved output quality is not as good as the output quality from the higher resolution pen of the multi-resolution pen set. Typically in inkjet printers, one print cartridge is black, another is a tri-compartment color cartridge, or a separate color cartridge is provided for each color component (e.g., cyan, magenta, yellow). The different types of nozzle arrays and differently designed color and black print cartridges, as well as other unique printhead characteristics all create the need for an inexpensive but reliable way to successfully mount such different cartridges into the same carriage. BRIEF SUMMARY OF THE INVENTION A principal object of the invention is to incorporate printheads having different types of electrical interconnects into the same carriage in order to expand the capabilities of the printer to achieve high quality printing as well as greater throughput. A related object is to decrease research and development costs as well as decrease the time for bringing higher resolution printers to market. It is a primary object of the invention to adapt a print carriage for removably mounting differently configured print cartridges at the same time in the same carriage without having to change the datum configuration for the print cartridges. Another object is to provide a modified interconnect scheme for a carriage mounted flex-circuit member having an increased number of conductive pads spread over an enlarged area without having to change the size of the carriage chute for receiving a print cartridge. A related object is to provide a simplified unitary resilient member made of foam or the like which assures pressurized interconnection of all of the increased number of conductive pads over their enlarged area. A further object is to provide an interconnect scheme which allows removably mounted print cartridges with different nozzle array densities activated by differently configured conductive pad arrays to be simultaneously seated in a carriage having substantially identical mounting chutes. The invention is specified in the Claims hereinafter. In its preferred form, the invention provides a modular carriage having a customized flex-circuit frame for interconnecting three separate color printheads each having thirty-two conductive interconnect pads in a four-column array in conjunction with a first corresponding resilient scheme, as well as for interconnecting at the same time a single separate black printhead having fifty-two conductive interconnect pads in a six-column array in conjunction with a newly developed resilient scheme. The color printheads each have approximately one-hundred nozzles arrayed in a swath of approximately 0.847 cm (1/3 inch) to achieve a 300 dpi resolution, and the black printhead has three-hundred nozzles arrayed in a 1.27 cm (1/2 inch) swath in order to achieve a 600 dpi print resolution. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a typical inkjet printer which can incorporate the apparatus and method of the present invention; FIG. 2 shows a carriage having removable multi-color print cartridges, which can incorporated the apparatus and method of the present invention; FIG. 3 shows an exemplary lower resolution color inkjet print cartridge used in a presently preferred embodiment of the invention; FIG. 4 is a perspective view of a carriage incorporating presently preferred embodiment of the invention in an inkjet printer; FIG. 5 is a top view of the carriage of FIG. 4; FIG. 6 is a fragmentary view of the flex-circuit interconnect on the carriage of FIGS. 4 and 5, with the interior carriage walls cut away; FIG. 7 is a schematic block diagram of the presently preferred embodiment of the invention; FIG. 8 is a schematic bottom view as seen looking up from the media showing the alignment relationship of the nozzle arrays of FIG. 7; FIG. 9 is a schematic view showing the use of a foam member for operatively connecting a flex-circuit to a higher resolution black inkjet cartridge; FIG. 10 is an exploded view showing a flex-circuit frame portion of a carriage, with the foam member of FIG. 9 for assuring pressure connection of a flex-circuit to a higher resolution black inkjet cartridge, and a metal spring member for assuring pressure connection of a flex-circuit to lower resolution color inkjet cartridges; FIG. 11 is a front view of the flex-circuit frame of FIG. 10; and FIG. 12 is a schematic diagram showing the relative resolution between a 600 dpi printout of the black printheads and a 300 dpi printout of the color printheads of a presently preferred embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In a multiple pen printer, it is important to improve the output quality of a printed page and increase the speed at which that output can be obtained as economically and simply as possible. In a printer mechanism, the output quality of a printed page is a function of printhead resolution. The higher the resolution the better the print quality. Also, in a swath printer employing a scanning carriage, the speed at which the output can be obtained is a function of the width of the swath which is covered by the printhead. In current multi-pen printers, each pen has the same resolution and usually the same swath width. This means that all the supporting structure, mechanics and electronics needs to be scaled up to support the resolution of the entire set of pens. All this hardware is more expensive than the hardware to support a multi-resolution, multi-swath width pen set where one pen is at the higher resolution and larger width that is desired and the other pens in the set are at a lower resolution and smaller size. This invention provides the benefits of a higher resolution, larger swath pen in lower resolution, smaller swath pens in the same printing machine. The higher performance pen can be used to improve output quality by enhancing certain key features that appear frequently in a printed page such as text. Such a pen also improves thoughput by being able to print these frequent features faster. The other lower performance pens can be used for less frequent or less demanding features such as graphics. In the presently preferred embodiment of the invention disclosed herein, we have combined a 600 dpi 1.27 cm (1/2 inch) swath black pen with three 300 dpi color pens each generating a swath of approximately 0.847 cm (1/3 inch). The high performance black pen is typically used for printing text and other "black only" features, and thus the output quality and throughput of these features is greater. It also improves the output quality of color graphics and color features by teaming with the three lower performance color pens when printing color graphics or color features. The black component of the graphics which is often a large portion of color graphics content is at a higher resolution and thus at a higher output quality level. The larger swath can then be combined with printing algorithms to improve the throughput of color graphics. Even though the invention can be used in any printing environment where text and/or graphics are applied to media using monochrome and/or color comoponents, the presently preferred embodiment of the invention is used in an inkjet printer of the type shown in FIG. 1. In particular, inkjet printer 10 includes an input tray 12 containing sheets of media 14 which pass through a print zone, and are fed past an exit 18 into an output tray 16. Referring to FIGS. 1-2, a movable carriage 20 holds print cartridges 22, 24, 26, and 28 which respectively hold yellow (Y), magenta (M), cyan (C) and black (K) inks. The front of the carriage has a support bumper 30 which rides along a guide 32 while the back of the carriage has multiple bushings such as 34 which ride along slide rod 36. The position of the carriage as it traverses back and forth across the media is determined from an encoder strip 38 in order to be sure that the various ink nozzles on each print cartridge are selectively fired at the appropriate time during a carriage scan. Referring to FIGS. 3-6, a 300 dpi color inkjet cartridge 40 having a tab-circuit with a four column thirty-two pad electrical interconnect 42 is removably installed in three chutes 44, 46, 48 of a unitary carriage 50. A flex-circuit member 52 having three matching sets of conductive pads 54, 56, 58 is mounted on flex-frame pins 60 for operative engagement with the cartridge pads when the cartridge is inserted into its appropriate chute. An enlarged set of conductive pads 62 covering a larger area, having a different layout, and constituting an array of six columns totaling fifty-two conductive pads on the flex-circuit member is designed for operative engagement with cartridge pads on a 600 dpi black injet cartridge 64 (see FIG. 9). Because of the differently configured electrical interconnect on the 600 dpi cartridge, and in order to avoid substantially changing the existing X/Y/Z datum configuration of the carriage, a unique interconnect scheme is employed. In that regard, the X-axis cartridge datums 65 engage the X-axis carriage datums 66, and the Y-axis cartridge datums 67 engage the Y-axis carriage datums 68, and the Z-axis cartridge datums 69 engage the Z-axis carriage datums 70. As best shown in FIGS. 9-1l, a previously existing spring assembly including a backing sheet 74, a plate 76 and a gimbal spring 78 are sized for fitting into apertures 80 of flex-circuit frame 82 to assure proper electrical interconnection for the three color cartridges. A unique spring assembly for the 600 dpi cartridge interconnect includes an unitary resilient foam member 84 which fits in a seat 86 which is larger than the aperture 80. A mounting peg 88 fits into matching hole 90 which along with bottom and lower ledges 91, 93 and upper side and top ledges 92, 94 hold the foam member in proper position to assure operative engagement across the electrical interconnect. circuit frame, which has been modified to incorporate the unique features of the present invention, is described more fully in copending applications identified above and incorporated herein by FIGS. 7-8 show the preferred mounting relationship between a 300 dpi nozzle array 96 of the color printheads and a 600 dpi nozzle array 98 of the black printhead. Control circuitry 99 on the substrate enables the three hundred firing resistors of the black printhead to be controlled through fifty-two electrical interconnect pads, and similarly enables all one hundred four firing resistors of each color printhead to be controlled through thirty-two electrical interconnect pads. FIG. 12 schematically shows the difference between the 300 dpi printout produced by the color pens (i.e., pen cartridges) and the 600 dpi printout of the black pen of the preferred embodiment described herein. Of course, it would be possible to incorporated different combinations of resolution in different printheads wherein the resolution difference may be arbitrary, depending on the printheads available and already developed, or wherein the resolution difference may be decimally related (e.g., 20% greater resolution, 30% greater resolution, etc.) or fractionally related (300dpi with 400 dpi; 300 dpi with 450 dpi, etc.). In that regard, the invention can be implemented with any of the existing inkjet cartridges which are currently available, with the best results occurring with printheads in the range of 180 dpi or greater. It will therefore be appreciated by those skilled in the art that the invention as shown and described herein allows different types of interconnects and different types of print cartridges such as cartridges of different print resolutions to be used in one product. This invention allows higher resolution and speed to occur for frequently printed features such as text and the most frequent color components of graphics such as black. Thus by printing these frequent features and components faster and at a higher resolution, the entire page is faster and of higher quality and is more comprable with laser printing performance (8+ pages per minute) and laser printing quality (600 dpi resolution). The new form of resilient interconnect member disclosed herein allows for optimization and customization for the particular contact pattern of different cartridges in the same carriage. Thus, the size of the carriage and the way that the cartridge is held in the carriage has to change very little between subsequent generations of printers. In other words, the required design change to the printer is minimized, the carriage does not have to grow wider nor taller, and the printer does not have to grow wider nor taller.

Claims: A printer/plotter (10) with a carriage for removably mounting at the same time a plurality of printheads, comprising: a frame for holding media (14) in a print zone; a carriage (50) movably supported on said frame for traversal over said print zone along a horizontal carriage axis; a first printhead (64) having first electrical interconnect means (52) for receiving a first set of print activation signals; a second printhead (40) having a second electrical interconnect means (42) for receiving a second set of print activation signals; means for mounting said first and second printheads on said carriage in adjacent first and second carriage chutes along said carriage axis, for printing by said first and second printhead of respective horizontal swaths on the media in said print zone, said mounting means further including: a first conductive assembly within said first chute for mechanically and electrically engaging said first electrical interconnect means, said first conductive assembly including: a first array of conductive pads (62) matching said first electrical interconnect means and first resilient means (84) extending from a first recess or aperture within said first chute and coextensive with said first array for maintaining a pressurized interconnection with said first electrical interconnect means when said first printhead is mounted in said first chute, and a second conductive assembly within said second chute for mechanically and electrically engaging said second electrical interconnect means through a second recess or aperture in said carriage, said second conductive assembly including a second array of conductive pads (74) matching all of said second electrical interconnect means but not matching all of said first electrical interconnect means, and second resilient means (76,78) extending from a second recess or aperture within said second chute and coextensive with said second array for maintaining a pressurized interconnection with said second electrical interconnect means when said second printhead is mounted in said second chute, wherein said first and second printhead each have a same external size and a same external datum configuration (65,67,69), said adjacent carriage chutes each have a same predetermined chute width along said carriage axis, said first array covers a larger area than said second array, and said first array has a greater number of columns of conductive pads along said carriage axis than said second array. A printer/plotter according to claim 1 wherein said first type of printhead includes a black printhead and said second type of printhead includes a color printhead. A printer/plotter according to claim 2 wherein said color printhead generates a color component selected from cyan, magenta, yellow, red, green and blue. A printer/plotter according to any preceding claim wherein said first type of printhead has a wider printing swath in a direction normal to said carriage axis than said second printhead. A printer/plotter according to any preceding claim wherein said first type of printhead has a higher resolution than said second printhead. A printer/plotter according to any preceding claim wherein said second type of printhead includes three adjacent color printheads each associated with a different color component, and any two adjacent ones of the first and second types of printheads have a same center-to-center spacing. A printer/plotter according to any preceding claim wherein said first resilient means is different in construction and operation from said second resilient means, said first resilient means includes foam means (84) for operatively engaging said first electrical interconnect means, and said second resilient means includes metal spring means (78) for operatively engaging said second electrical interconnect means.

Inventors: AZMOON MAJID, HARRIS DONALD G, NOBEL GARY M, AZMOON, MAJID, HARRIS, DONALD G., NOBEL, GARY M.
Applicants: HEWLETT PACKARD CO, HEWLETT-PACKARD COMPANY
Application year: 1994
Main classification: B41J25
IPC codes: H05K3, B41J29, B41J2, B41J25